Throttle control mechanism



c. L. CUMMINs 2,034,743!

THROTTLE CONTROL MECHANISM I' Filed oct. 2e, 1934 Patented Mar. 24, 1936 UNITED STATES PATENT OFFICE THROTTLE CONTROL MECHANISM Application October 26, 1934, Serial No. 750,127

2 Claims.

My invention relates to a throttle control mechanism for internal combustion engines, particularly oil engines, and is concerned primarily with a mechanism for preventing the movement of the throttle to full open position until the vehicle propelled, or generally the load moved, thereby has attained a predetermined speed.

It is characteristic of oil engines that practically their full power is available when starting under load. This condition is advantageous where the principal operative requirement is rapid acceleration, but is a positive detriment unless properly controlled where, for example, the engine furnishes the motive power for a shifting locomotive in a railroad yard. Because of the high starting torque of the engine, the tendency of the shifting crew is to couple as many cars as the locomotive is capable of moving from a standing start, with the result that the train cannot be accelerated and therefore is moved at a slower rate of speed than is demanded by eicient shifting service.

It is therefore desirable to provide a mechanism which prevents the utilization of the full power of the engine when starting under load by interposing a stop in the path of movement of the throttle lever short of the latters full load position, and which is automatically shifted to a clear position when the locomotive, for eX- ample, attains a predetermined speed, and further, in which the relation between the stop and throttle lever is such that the latter may be moved from full-load to no-load position, notwithstanding that the stop may then be occupying an interrupting position due to a decrease in the train speed. Three solutions of this problem are disclosed in my copending application, Serial No. 714,796, filed March 9, 1934.

The principal object of the present invention is to devise a mechanism having the above characteristic which is adapted for operation by one of the power sources that are customarily available on track vehicles, for example, namely, air that is ordinarily employed, for braking purposes.

These and further objects of my invention will be Set forth in the following specification, reference being had to the accompanying drawing, and the novel means by which said objects are eiectuated will be definitely pointed out in the claims.

In the drawing, the ligure is a diagrammatic view, partly in section, showing a mechanically controlled, air circuit for limiting the movement of the throttle lever towards full-load position, the lever being shown in the maximum position which it may assume until the locomotive attains a predetermined speed.

Referring to the drawing, the numeral I designates the wheel of a locomotive, for example, which is mounted on the usual axle II that may have aixed thereto a pulley I2. A belt I3 operates over the'pulley I2 and also over a second pulley Id secured to a shaft I5 which is journaled in a suitable bearing I6. The shaft I5 extends to the left of the bearing and has aixed thereto a pair of arms I'I upon which are pivotally mounted a pair of iiy-ball levers I8, the inner arms I9 of which are in constant bearing engagement with one end of a sleeve 26 that is journaled upon an extension 2! of the shaft I5. The left end oi the sleeve is formed with an annular channel 22 and a coil spring 23, which encircles the left extremity of the extension 2|, bears against the left end of the sleeve and also against the head 24 provided on the extension 2l. rlhe tendency of the spring 23 to extend in length causes the sleeve 23 to bear constantly against the lever arms i9.

The annular channel 22 permanently engages with the upper end of a rock arm 45 which is xed upon a projecting end 46 of a common type of rotary valve (not shown) which is rotatably mounted within a casing 4l. This casing is in communication by means of a pipe 48 with the usual air compressor, for example, and also by means of a pipe 49 with a cylinder 50. A piston 5I is reciprocably mounted in the cylinder 5i) and is provided with a piston rod 52 which projects without the cylinder and operates as a stop for the lower end of a throttle lever 53 that is pivoted as at 51. A coil spring 54 is disposed in the cylinder below the piston 5I and normally tends to maintain the stop' 52 in the throttle lever interrupting position shown. The no-load position of the throttle lever is indicated by the dotted line 58 and the fullload position by the dotted line 59, the lever being shown in the maximum position to which it can be moved owing to its engagement with the stop 52. Preferably, the lower end of the lever 53 and the upper end of the stop 52 are provided with inclined cam surfaces 55 and 56, respectively, so that the throttle lever can be returned to the no-load position from any position between the intermediate position, as shown, and the full-load position, notwithstanding that the stop 52 may be occupying the position shown in the drawing. A situation of this kind might occur, for example, when the locomotive is ascending a grade with the throttle lever in full-load position and it is desired to bring the train to a stop. During this return movement, it will be obvious that the cam surfaces will cause the stop 52 to be moved downwardly until the lever 53 has cleared the upper end of the stop. It will be understood that the delivery end of the pipe 49 is located to introduce air into the cylinder 50 above the piston 5I in all positions that the latter may assume, and that, for the position of the parts as shown, the valve in the casing 41 is so disposed that communication is denied between the pipes 48 and 49. In the relation of the parts as shown, the interrupting position of the stop 52 is indicated as permitting a movement of the throttle lever through approximately two-thirds of its range from the no-load position, although this relation may be varied as desired. In the operation of this mechanism, the fly-balls I8 will be adjusted so that, at some predetermined speed of the locomotive, they will move outwardly suicient to cause the sliding of the sleeve 2Q toward the left and consequently a rocking of the arm 45 to a position in which the pipes 48 and 4B are placed in communication, thus establishing pressure within the cylinder 5B and moving the piston 5l downwardly to permit continued movement of the throttle lever toward its full-load position. This releasing movement of the fly-balls may be set for as low as a speed of five miles per hour, or at any speed at which the operating requirements demand. When the speed of the locomotive falls below the indicated critical speed, the stop 52 will be returned to interrupting position by the spring 54 and in order to insure free action of the spring at this time, the rotary valve may be arranged to insure bleeding of the air from the space above the piston 5|. In other words, when the parts are in the position shown in the drawing, the space above the piston 5| may be in communication with the atmosphere through the rotary valve.

It is apparent that the shifting crew is positively prevented from coupling more cars to the locomotive than the latter can initially move for the throttle opening indicated. Therefore, there is always provided a suflcient reserve of power to insure a desirable acceleration ofY the coupled train and it is contemplated that, after the mechanism is once adjusted, it will be incapable of unauthorized change by the train crew. Moreover, the mechanism is designed to make use of a source of power that is customarily available in railway service, so that no additional auxiliaries are required.

It is to be understood, however, that no restrictive interpretation is to be placed on the application of my mechanism to the fleld of railway service, in View of the above disclosure, since the'essential conception involved is capable of other and broader uses in the art of engine controls. For example, in hoisting apparatus, crane or steam shovel installations and similar appliances, it may be desirable to arrange for a power reserve, such that the load which the engine could initially move would be restricted to a degree permitting subsequent acceleration. The term vehicle, therefore, is employed in its broader aspect as being an instrument of conveyance.

I claim:

1. A throttle control mechanism for an engine driven vehicle comp-rising in combination, a throttle lever operable between no-load and full-load positions, a cylinder, a piston operable in the cylinder and having a stop projecting externally thereof, means tending to hold the stop in a position to limit the movement of the lever to a predetermined intermediate position when moved toward full-load position, a mechanical governor device, controlled by the speed of the vehicle, a source of fluid power connected by a feed line to the cylinder, valve means closing the line below a predetermined speed of the vehicle, and means actuated by the governor device to open the valve means to thereby establish a pressure in the cylinder sumcient to shift the stop from lever-interrupting position when the vehicle attains a predetermined speed.

2. A throttle control mechanism for an engine driven vehicle comprising in combination, a throttle lever operable between no1-load and full-load positions, a cylinder, a piston operable in the cylinder and having a stop projecting externally thereof, a spring in the cylinder tending to hold the stop in a position to limit the movement of the lever to a predetermined intermediate position when moved toward full-load position, a mechanical governor device controlled by the speed of the vehicle, a source of fluid power connected by a feed line to the cylinder, rotary valve means in the line closing the same below a predetermined speed of the vehicle, and a rock arm connected to the valve and actuated by the governor device to open the valve to thereby establish a pressure in the cylinder sulicient to shift the stop from lever-interrupting position when the vehicle attains a predetermined speed.

CLESSIE L. CUMMINS. 

